PCF5079T Просмотр технического описания (PDF) - Philips Electronics

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PCF5079T

Dual-band power amplifier controller for GSM, PCN and DCS

Philips Electronics 

Philips Semiconductors

Dual-band power amplifier controller for

GSM, PCN and DCS

Product specification

PCF5079

12.2 PA protection against mismatch

High VSWR at the PA output may occur in systems where

the PA is connected to the antenna via couplers and

switches with low insertion loss, depending on the antenna

matching. The incident and reflected power have to be

monitored and care has to be taken to prevent the

summed RF power does not exceed the defined maximum

value at the PA output.

As two sensor inputs are available in the PCF5079, two

different detector signals can be combined: one for direct

path and one for reflected path. These two voltages, fed to

the sensor inputs, are summed inside the PCF5079

resulting in a decrease in the PA output power if there is an

increase of the VSWR at the antenna port (see Fig.15).

handbook, full pagewidth

PA

RFin HB

RFin LB

band select

switch

broad band

coupler

RFout

C1

VS1

R1

D1

C2

VS2

R2

D2

MGT330

Fig.15 Example of PA mismatch protection circuit.

Table 3 Table of components (see Fig.15)

SYMBOL

D1, D2

R1, R2

C1, C2

−

−

COMPONENT

detector diode

resistor

capacitor

band select switch

broad band coupler

DESCRIPTION

Philips 1PS79SB62

R = 1 kΩ (decoupling versions)

C = 39 pF

Motorola; Alpha Industries; M/A; COM GaAs MMIC; or discrete pin diode,

e.g. Philips BAP51-03

Murata LCD20 series; TDK HHM 20, 22 series

2001 Nov 21

17

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